Itching — A Diabolical, Peculiar, Often Unsolvable Problem
November 20, 2017 at 3:45 p.m.
By Max [email protected]
While this case is extremely rare, many of us have had been plagued with some condition where itching occurs. In fact, relentless itching has been described as among the most distressing of all physical sensations.
While itching is technically merely a symptom, it affects a patient’s quality of life. Moreover, mental processes are involved that help explain why it feels good to scratch.
Within the past decade, there has been a flurry of research into what causes itching and how scratching helps to stop it. Along with brain imaging, studies have begun to look at gene activity and to map the signals that flow between cells in the skin and the immune system. It has been discovered that itching and scratching engage a number of brain areas. There is still much to learn, however.
Acute itching, such as from an insect bite, is often temporary and annoying and can be treated just by scratching. Chronic pruritus, on the other hand, is defined as an itch persisting for more than six weeks. It may involve the entire skin or only particular areas, such as the scalp, upper back, arms or groin.
Itching is an extraordinarily common symptom. All kinds of dermatological conditions can cause it: allergic reactions, bacterial or fungal infections, skin cancer, psoriasis, dandruff, scabies, lice, poison ivy, sun damage or just dry skin. Plenty of non-skin conditions can also cause itching, including hyperthyroidism, iron deficiency, liver disease, cancers like Hodgkin’s lymphoma and psychogenic disorders.
The No. 1 cause of chronic itch is eczema. A recent survey shows that about 1.8 million Americans report suffering from the chronic form of eczema, about 6 percent of the population in the United States. In the Western hemisphere, around 20 percent of children have chronic eczema. Recent research indicates that the underlying cause for the inflammation is a toxin-producing bacteria found on the surface of the skin. Ninety percent of patients with eczema have exceedingly high numbers of bacteria on their inflamed skin.
Itching worsens at night in many systemic and skin diseases. Up to 65 percent of patients with inflammatory skin conditions including psoriasis, atopic dermatitis and other unknown causes have reported increased itching at night. Changes in skin physiology, such as temperature and barrier function, may also play a role. Itching has been reported to be aggravated by warm temperatures and it has been suggested that heat can increase itch sensation by its effect on nerve endings. Although several types of temporary remedies are available — both over-the-counter and prescription — that may relieve non specific pruritus, the lack of treatments for nighttime itching is astonishing and alarming.
Scratching is a natural response to an itch, and by definition, inseparable from it. The itch-scratch cycle is a complex phenomenon that involves sensory, motor and emotional components. It is well-known that the urge to scratch can be remarkably intense, since the reward provided by scratching brings not only itch relief but associated feelings of pleasure as well.
Itching and scratching engage brain areas involved not only in sensation, but also in mental processes that help explain why we scratch, including motivation and reward, pleasure, craving and even addiction. What an itch turns on, a scratch turns off. Scratching may be the only way to relieve atopic eczema.
In chronic eczema, the more the patient scratches, the more damage occurs to upper nerve layers of the skin barrier. These nerve fibers become overactivated so that scratching actually intensifies the perception of itch, causing greater itching. Scratching is also widespread in the animal kingdom, although no one knows for sure why animals claw, bite or peck themselves.
Treatment of chronic pruritus should be directed to the underlying cause when possible. In the initial treatment of symptoms, the use of mild cleansers, topical anesthetics and coolants may be helpful. Topical steroids, however, are the primary treatment because they help to reduce inflammation.
It is also important to apply moisturizers to protect the upper layer of the skin. The reason is that water loss from the skin increases at night. Antihistamines that cause drowsiness may also be used, primarily to help a patient sleep. For some unknown reason, babies born in a home with a dog during pregnancy receive protection from allergic eczema that lasts until approximately age 10.
No drug specifically designed to treat chronic itching, regardless of disease origin, has been approved by the Food and Drug Administration. One investigational one, however, appears promising, but approval may be years away. For many patients, new treatments cannot come soon enough.
Max Sherman is a medical writer and pharmacist retired from the medical device industry. He has taught college courses on regulatory and compliance issues at Ivy Tech, Grace College and Butler University. Sherman has an unquenchable thirst for knowledge on all levels. Eclectic Science, the title of his column, will touch on famed doctors and scientists, human senses, aging, various diseases, and little-known facts about many species, including their contributions to scientific research. He can be reached by email at [email protected].
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While this case is extremely rare, many of us have had been plagued with some condition where itching occurs. In fact, relentless itching has been described as among the most distressing of all physical sensations.
While itching is technically merely a symptom, it affects a patient’s quality of life. Moreover, mental processes are involved that help explain why it feels good to scratch.
Within the past decade, there has been a flurry of research into what causes itching and how scratching helps to stop it. Along with brain imaging, studies have begun to look at gene activity and to map the signals that flow between cells in the skin and the immune system. It has been discovered that itching and scratching engage a number of brain areas. There is still much to learn, however.
Acute itching, such as from an insect bite, is often temporary and annoying and can be treated just by scratching. Chronic pruritus, on the other hand, is defined as an itch persisting for more than six weeks. It may involve the entire skin or only particular areas, such as the scalp, upper back, arms or groin.
Itching is an extraordinarily common symptom. All kinds of dermatological conditions can cause it: allergic reactions, bacterial or fungal infections, skin cancer, psoriasis, dandruff, scabies, lice, poison ivy, sun damage or just dry skin. Plenty of non-skin conditions can also cause itching, including hyperthyroidism, iron deficiency, liver disease, cancers like Hodgkin’s lymphoma and psychogenic disorders.
The No. 1 cause of chronic itch is eczema. A recent survey shows that about 1.8 million Americans report suffering from the chronic form of eczema, about 6 percent of the population in the United States. In the Western hemisphere, around 20 percent of children have chronic eczema. Recent research indicates that the underlying cause for the inflammation is a toxin-producing bacteria found on the surface of the skin. Ninety percent of patients with eczema have exceedingly high numbers of bacteria on their inflamed skin.
Itching worsens at night in many systemic and skin diseases. Up to 65 percent of patients with inflammatory skin conditions including psoriasis, atopic dermatitis and other unknown causes have reported increased itching at night. Changes in skin physiology, such as temperature and barrier function, may also play a role. Itching has been reported to be aggravated by warm temperatures and it has been suggested that heat can increase itch sensation by its effect on nerve endings. Although several types of temporary remedies are available — both over-the-counter and prescription — that may relieve non specific pruritus, the lack of treatments for nighttime itching is astonishing and alarming.
Scratching is a natural response to an itch, and by definition, inseparable from it. The itch-scratch cycle is a complex phenomenon that involves sensory, motor and emotional components. It is well-known that the urge to scratch can be remarkably intense, since the reward provided by scratching brings not only itch relief but associated feelings of pleasure as well.
Itching and scratching engage brain areas involved not only in sensation, but also in mental processes that help explain why we scratch, including motivation and reward, pleasure, craving and even addiction. What an itch turns on, a scratch turns off. Scratching may be the only way to relieve atopic eczema.
In chronic eczema, the more the patient scratches, the more damage occurs to upper nerve layers of the skin barrier. These nerve fibers become overactivated so that scratching actually intensifies the perception of itch, causing greater itching. Scratching is also widespread in the animal kingdom, although no one knows for sure why animals claw, bite or peck themselves.
Treatment of chronic pruritus should be directed to the underlying cause when possible. In the initial treatment of symptoms, the use of mild cleansers, topical anesthetics and coolants may be helpful. Topical steroids, however, are the primary treatment because they help to reduce inflammation.
It is also important to apply moisturizers to protect the upper layer of the skin. The reason is that water loss from the skin increases at night. Antihistamines that cause drowsiness may also be used, primarily to help a patient sleep. For some unknown reason, babies born in a home with a dog during pregnancy receive protection from allergic eczema that lasts until approximately age 10.
No drug specifically designed to treat chronic itching, regardless of disease origin, has been approved by the Food and Drug Administration. One investigational one, however, appears promising, but approval may be years away. For many patients, new treatments cannot come soon enough.
Max Sherman is a medical writer and pharmacist retired from the medical device industry. He has taught college courses on regulatory and compliance issues at Ivy Tech, Grace College and Butler University. Sherman has an unquenchable thirst for knowledge on all levels. Eclectic Science, the title of his column, will touch on famed doctors and scientists, human senses, aging, various diseases, and little-known facts about many species, including their contributions to scientific research. He can be reached by email at [email protected].
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